Two-cycle engine.



H. H. ABBOTT.

TWO-CYCLE ENGINE.

APPLlcATioN FILED N0v.8,1913.

1,1'75,107. Patentod Mau'. H, 1916.

'carica HENRY H. ABBOTT, F COLDWATER, MICHIGAN.

TWO-CYCLE ENGINE.

Specification of Letters Patent.

Patented Mar. it, 1916# Application led November'8, 1913. Serial No. 799,928:

To all whom it may concern:

Be it known that I, yHENRY H. ABBo'rl, a citizen of the Unitedr States, residing at Coldwater, in the county of Branch and State of Michigan, haveinvented certain new and useful Improvements in Two-Cycle Engines, of which the following i's a speciication. Y

My invention relates to that type of in. ternal combustion engines in which a vacuum is developed on the explosion stroke and communicated to the explosion chamber to assist iny scavenging at the end of that stroke, and particularly to those embodiments of the'principle which use both preliminary and main exhausts.A

The object of my invention is-to get compression ofthe entire charge' by cutting oii both preliminary and main exhausts before the compression stroke; also to avoid waste by delaying intake of. new char euntil after scavenging has commenced; a so to insure pure mixture around i 4iter by locating the same in an oiset cham er atopposite end of piston stroke from exhaust ports; and withl these and minor objects in view mymvenf tion consists of the parts and combination of parts as will-be more fully hereinafterl pointed out. v

In the drawing z-Figure 1. is a longi: tudinal section through the cylinder crank case and immediately associated parts of an explosive engine. Fig. 2 is a detail sectionaly view -of the rotary exhaust valve, and its casing, the valve being in elevation. Fig, 3

, is a tranverse section on the line 3-'-3 Fig. 2.

The reference numeral 1 designates a cyl- ;...inder for a two cycle en 'ne which has two interior diameters; that 1s to say the upper part of cylinder 2 is of less diameter than the lower Ypart 3 of the cylinder.-

4 is the crank case.

5 is the inlet pipe. y

6 is apiston aving two diameters corresponding with the two diameters ofthe cylinder, the lower portion ,7 of the pistn constituting the larger diameter thereof.

8 is a crank mounted on a suitable shaft.

9 is a crank pinA on which the connecting rod 10 is pivoted, said connecting rod being secured at its upper end as at 11 to the piston. l

12 is a plug screwed into the cylinder above the valve 20. 13 `is the preliminary exhaust port and 14 1S the mam or second exhaust port.v

15 is an exhaust pipev re istering withthe exhaust port 13 and provi ed with a rotary valve 16 havinga port 17 adapted, to registerwith the'exhaust port 13. It will be noted that the exhaust pipe 15 has a water space 18. v y

20: is. a valvewhich controls theopening into the chamber 29 and `is held on its lseat by the spring 21, one end of said spring being seated on a shoulder integral with chamber 30, while the other end is seated on the washer 22, said washer being held in place by the pin 23. 26 is a push rod which Yis operated by the' cam 27 imparting its motion in turn tothe valve20. 28 -is a earbureter connected ber 30 by the pipe A5.

25 is an exhaustpassage, one end communicating with the'enlarged diameter at the lower portion of the cylinder and the to the chamother end communicating with the exhaust pipe 15. .v l

2a, Fig. 2, is Aa port'in rotary valve 16 lEvhich controls the opening int a chamer 25. f

with the piston 6 at the top of the stroke and a 'charge .of explosive mixture fully compressed,4 ignition takes place increasing the 'pressure and vforcing the piston down. As the piston nears the lower end of the stroke, the preliminary exhaust port 13 is opened and the gases rush into the exhaust pipe 15 through the rotary valve 16 and 1ts port 17 and reduce vthe pressure in chamber 2 to about that of atmosphere, the position of port 17 being now such asto permit this; but when the lower edgelof the' exhaust port 13 has been passed by the piston 6 and before the upper edge of the jsecond exhaust port 14 is passed, the movement "of the rotary valve hasclosed the port 13, 'so that rione of the gases can return into the cylinder. Inthe meantime, the piston, on its travel downward,'has created a vacuum in the enlarged diameter 3 of the cylinder and the instant that the .upper edge of thepiston has passed the upper edge of the second exhaust4 port 14, the remainmg gases in the cylinder expand into the space 3, thus greatly reducing the residual products of combustionin chamber'! and vcreating a partial vacuum therein. f Thevalve 20l is now opened and atmosphere,r rushesl'through the carbureter 28, takingy up theyfuelconstituent, then' through passage 30, and pastv The operation is as follows; -Beginning,

valve 20, into chamber 29 and thence into .chamber 2 to relieve the vacuum in the latter, and present the new charge ready for compression. The proportion of burned charge remaining in chamber 2, encountered by. incoming new charge, is small, and-is evenffurther reduced in volume as it gives oli some of its heat to thelnew fuel mixture. fOn the up-stroke of the piston, the valve 20 is closed so that the charge in chamber 2 is compressed ready for the next lgmtlon.,4 At the same time, the burned gas vin chamber 3 is, forced .out nto'chamber 25 and thence into exhaust pipe 15, the port 24 l arrived in position to permit this. When in the rotary valve having in the meantime the iston 6 has reached the end-of the up- Stro e, or thereabout, the rotary valve has moved to shut oi' communication with the chamber 25, and the cycle of movements Acommencing with ignition, may nowherepeated. l

Inasmuch as the rotary exhaust valve n its control of port 13 is used only for discharging the burned gases until'pressure in the cylinder 2 ,is lowered down to that of theY atmosphere (or slightly below atmosphere if we regard the residual suction eiect of the ases speeding through the exhaust passage it is essential that it should open as `late in the expansion stroke as possible and movement of vthe piston begins to raise the pressure the chamber 3, asv well as in chamber 2, there lis no tendency to expel an of the new charge through the ports 14. t

will, therefore, be seen that whereas in engines of ordinary construction, less than the entire new charge` is compressedA owing to the'lap or delay in closing the exhaust port,

charge ,the

and to the suction produced'by 'the momentum of the exhaust gases 'stlll moving rapidly through the exhaust passage at the commencement of the upward stroke, neither of these influences exists in theypresent construction, for the reason that -the primary exhaust port 17`is1closed before-the intake valve 201s openv and ythe second exhaust outlet 25 isnot opened until. the return movement ofy the piston has commenced and pressure consequently begins to v rise in the chamber 3. In `other wor the use of the rotary valve,- makes it 1possible to compress the cngth of the stroke.and

is a result none Vof the explosive .mixture is ost. p

All 'of the objectionable features of the crank-case compression type of two cycle engines are eliminated by my invention because I do not employ crank-case compression to force the charge into the cylinders with the resultant loss vfrom leakage through bearings and the like; furthermore,y the drawing of the burned charge intothe lower enlarged diameter of the cylinder cools the charge considerably, lwhich results in thevgas shrinking and therebyeliminates 'a greater amount of burned gas from the chamber 2.

Backring cannot have the same results in an engine constructed according to my invention .as in the type of engines heretof fore usedwhere the, total amount of gas in the crank case is four or iive volumes. In my engine, only the gas between the inlet port 29 and the carbureter can back fire and this only occurs when the mixture is lean', and can be easily overcome; e

engine constructed in accordance with this invention, when throttled, has a reduction in pressure ofthe contents of the cylinder, under the pressure of the atmosphere, amounting to several pounds, which results in more positive introduction of the fuel charge into the cylinder; whereas the crankcase compression type has an increase of pressure in the crank case over the pressure of the cylinder, amounting to only a few ounces, which causes the introduction of the fuel charge into the cylinder to be very .uncertain, and results in irregular running and backring. v f

Inasmuch as the charge enters the cylinder at a point about the spark plu and thereby erfectly scavenges this portlon `of the cylinder, an explosion at every up-stroke of the piston is insured. The present construction will make a very flexible motor, 4

and one that will be of special advantage in driving automobiles, where great flexibility is very important.

1. A- two-cycle combustion engine having a combustion chamber containing a working piston and provided with a primary exhaust port, a vacuum chamber having a port of communication with the combustion chamber and removing residuall burned gases from and developmg vacuum in said combustion chamber, a suction4 fuel-feeding assage opening into the combustion cham er, a mechanically actuated valve for opening and closing the primar exhaust passage near the end of the wor ing stroke; means for opening said port of communication after the primary exhaust passage is closed, and a mechanically actuated valve for opening the fuel-feeding passage, timed to open the same only after communicationvhas been established between the combustion chamber and the vacuum chamber and while vacuum exists in said combustion chamber.

2. A two-cycle combustion engine having a combustion chamber containing a working piston and provided with a primary exhaust port, a vacuum chamber having a port of communication with the combustion chamber and removing residual burned gases from and developing vacuum in said combustion chamber, a suction fuel-feeding passage opening into the combustion chamber, a mechanically actuated Valve for opening. andclosing the primary exhaust passage near the end of the working stroke; means for opening said port of communication .after the primary exhaust passage is closed, and a mechanically actuated valve for opening the fuel-feeding passage, timed to open the same only after communication has been established between the combustion chamber and the vacuum chamber and while vacuum exists in said combustion chamber; the Working piston being also constructed and adapted to operate in the vacuum chamber for developing the vacuum therein and constituting the means for closing the port of communication between said vacuum chamber and the combustion chamber and timed to etl'ect said closure shortly after the commencement of the compression stroke of the piston, andl said piston operating to raise-.the pressure in the vacuum chamber, with its port-closing movement and thereby preventing flow of` fuel mixture through said port of communication as compression commences in the combustion chamber.

3. A two-cycle combustion engine having a combustion chamber containing a working piston and provided with a primary exhaust port, a vacuum chamber having a port of communication with the combustion chamber and removing residual burned gases from and developing vacuum-'in said combustion chamber, a suction fuel-feeding assage opening into the combustion cham er, a valve for positively opening and closing the primary exhaust passage near the end of the working stroke; means for opening said port of communication after the primary exhaust passage is closed, and a positively actuated valve for opening the fuelfeeding passage, timed to open the same only after communication has been established between the combustion chamber and the vacuum chamber and while vacuum exists in said combustion chamber; said piston being also adapted to operate in the vacuum chamber for developing vacuum therein and expelling products of combustion therefrom; said vacuum chamber being provided with a discharge port, and the Yprimary exhaust valve being also adapted to control the vacuum chamber exhaust port.

4. In an internal combustion engine, an explosion chamber, a vacuum chamber, a preliminary and a second exhaust passage communicating successively with the explosion chamber, said second exhaust passage being formed in part of the vacuum chamber, and a rotary valve controlling back How through both exhaust passages.

5. In an internal combustion engine, an explosion chamber, a vacuum chamber, a preliminary and a second exhaust passage communicating successively with the explosion chamber, said second exhaust passage being formed in part by the vacuum chamber, a valve casing forming part of both exhaust passages and a common rotary valve in said casing.

6. ln an internal combustion engine, an explosion chamber, a vacuum chamber, a preliminary and a second exhaust passage communicating successively with the explosion chamber, said second exhaust passage being formed in part by the vacuum chamber, a valve casing forming part of both exhaust passages, a rotary valve in said casing common to both of said exhaust passages and having a separate port for each exhaust passage.

The foregoing specification signed at Coldwater, Mich., this 18 day of October,

HARRY H. ABBOTT. In presence of two witnesses:

VERGIL C. Bowsnn,

RUTH E. HUNGERFORD. 

